Russia's actions in the Crimean peninsula are "of concern" to Latvia, according to the country's foreign minister.
Edgars Rinkevics said the "information warfare" being carried out by Russia after its troops entered the Ukrainian territory had reminded Latvians of the Soviet invasion of their country in 1940.
He told Sky News: "We are very much concerned about what is happening currently in Ukraine, but we are not hysterical of course.
"For many Latvians, all the events as they currently unfold in Ukraine do have some emotional feeling.
"We have gone through that in 1940, there is some resemblance to events of the 1930s and there is quite heavy Russian propaganda - I would call it 'information warfare'.
"Some of that information has been passed to Russian speakers in Latvia."
Mr Rinkevics called for more Nato assets to be placed on the ground in Ukraine to prevent any escalation.
And he said further sanctions could be necessary to deter Moscow from seizing more territory.
He said: "I certainly think if there is more escalation we will have to go to so-called phase three of sanctions - which including some embargoes on military equipment and also targeting some banking and trade issues.
"This is a step which is needed if Russian troops invade the eastern part of Ukraine or there is some kind of escalation."
The US is to give Moldova $10m (£6m) to strengthen security on its border with Ukraine, according to a top diplomat.
Victoria Nuland said part of Moldova's eastern border with Ukraine is occupied by the breakaway Russian-speaking region of Transdniestr.
The Russian action in Crimea has raised concerns it could make similar moves in other former Soviet states which contain separatist regions.
Officials in Transdniestr this month appealed to politicians in Moscow to pass legislation that could see the region absorbed into Russia.
On Saturday, Russia insisted it had no intention of sending armed forces into Ukraine despite a build-up of troops on the border.
In an interview on Russia TV, Foreign Minister Sergei Lavrov said: "We have absolutely no intention of - or interest in - crossing Ukraine's borders."
US officials estimate as many as 40,000 Russian troops have gathered close to the border, where they claim they have begun establishing supply lines.
On Friday, Russia announced all military bases in Crimea were under its control and Ukrainian troops have left the region.
Sanctions on key people close to President Vladimir Putin have been targeted by sanctions after Russia was accused of invading Crimea following the removal of President Viktor Yanukovych.
Crimea voted overwhelmingly in favour of joining Russia, but the referendum was denounced as invalid by the EU and US.